FE in normal AC & Automatic Climate Control. HELP!

Hi....

I have a Swift VDi now , which dont have a AUTOMATIC CLIMATE CONTROL AC , but a normal one.

Right now, im going to buy a new car, which will have a Auto Climate Control AC.

So, my question is, lets say, if we use AC in our drive, does it affect the FE ??

Or is there any difference in the performance of FE in Normal AC and Auto Climate Control AC ?

If we keep the Auto Climate Control switched on always, then is it going to hamper the FE or decrease it ?

What do you guys suggest ?

It will depend upon what is the temperature set by you in AC.

If the temp of cabin and AC is same then the compressor will switch off and only fan will run.

If temp is more than cabin temp than the heater will get activated and decrease FE.

If temp is less than cabin temp than the AC will work. Chilling your car and decreasing your FE.

Ok the main point is, when it has to cool the inside of the car, then the heater has to get activated and it will affect FE.

So, its better to keep the Automatic Climate Control Swithed off.  RIGHT ??

Then whats the difference between this and the normal AC ?

The heater won't decrease FE.  It works by running engine coolant through the heater core, which is basically a small radiator inside the car's climate control system.  Of course this also means that the heater won't work until the engine warms up.  If the heater wasn't on, the radiator would get rid of the excess heat anyway.

Auto climate control won't make much difference compared to normal AC.  Actually, if you could manage the car's temperature as well as auto climate control does, there would probably be no difference.  All auto AC really does is turn the knobs for you.  The rest of the system is the same.  The one thing auto AC will do that could decrease fuel economy compared to normal AC is that it will operate at maximum power when you get into a hot car and turn it on.  Of course you can do this in a car with normal AC as well.  Just set it to max until the car gets cooled off, then adjust it to a normal setting.

Auto climate control won't use the AC if the outside air is cool enough.  Instead it will just draw cool air from outside.  Thus if you have the temperature set for 25C in 10C weather, decide you're too warm, and lower it to 22C, it will just use the cool outside air to adjust the cabin temperature instead of the AC.  I'm not sure about the heater.  Since waste heat is essentially free, I don't care if the car uses the heater or not so I've never worried about the reverse of this situation.

You don't have to turn off auto climate control to turn off AC.  A lot of auto climate control systems have an AC button separate from the main auto climate on/off button.  The ones that don't (Ford, at least in the US) have mode selection buttons, and only the full auto, AC (may be 2 AC modes), and possibly defog/defrost settings will use the AC.  Other modes allow the car to use heat and outside air as needed.  Some cars will the AC and heater at the same time in defog mode.  AC also removes moisture from the air, and warm, dry air works best for defogging the windshield.  If your car does this, you can also use it to dry out the cabin on cold, rainy days.

Thanks Mike, for this informative post!

Hey Mike,

Brilliant post there! I wasn't sure as how heater works in the car. Thanks.

Great post bro. I need to test live and then I can compare and use accordingly. Thanks again.

So, whats the best thing to do in cars, which have Auto Climate Control ??

Keep it off ??

Keep it always on with low temp ?

Or keep it all auto ?

Keep it on in auto mode with a temperature you are comfortable with. The effect on FE is pretty marginal. Don't worry!

Ok cool..

Im comfortable with everything, which has lees effect on FE..

So, what temp do you suggest bro ?

In that case, I suggest you drive your car with windows open. The effect on FE would be significant. Lol.

Jokes apart, it's you and your comfort. Buy the car and try different temperature levels and then stick to a temperature you feel is a good balance. I think 23-25 would be fine.